The present invention is directed to an ophthalmic device and in particular to a device using a single linearly polarizing element (LPE) as a lens.
It has been found that reflected light always contains at least some net polarized component. The net polarization is not a function of brightness, but of illumination angle, (e.g., sun angle), materials being observed and observation angle. Thus net polarization and direction of maximum polarity present an additional dimension of image data not available to the naked eye.
There is a large body of literature describing LPE's for reducing glare and light transmission. When an LPE is oriented horizontally, for example, glare from a low sun is almost completely eliminated. There exists a large body of prior art, including Land's fundamental patent (U.S. Pat. No. 2,005,426), that describes devices for providing variable light transmission by employing a plurality of superimposed LPE's. In each case, the effect has been to reduce the light transmission below the ambient level and to vary that transmission equally in both eyes. Along different lines the U.S. patent issued to Morgan (U.S. Pat. No. 3,958,867) and prior art noted therein relates to adjustable lenses to permit the user to modify the positions of corrective lenses such as bifocals or to modify light transmission characteristics as in the case of sunglasses. Morgan's description is fundamentally no different from existing ophthalmologists' equipment of the early 20th century, that is used to prescribe corrective lenses. Such standard ophthalmic office equipment provides a plurality of lenses that attach to special eyeglass structures. The ophthalmologist can flip, rotate or otherwise orient the lenses over each eye independently by using a plurality of elements in each lens to provide a means for corrective lenses.